The present invention relates to a refrigerating cycle apparatus that has a throttle structure suitable to control a refrigerant flow and that is suitable to control a two-phase refrigerant, and further relates to an air conditioning apparatus that improves temperature and humidity controllability in a cooling or heating operation, reduces refrigerant flow noise, and improves comfort with respect to room temperature and humidity and noise. Further, the present invention relates to a low noise throttle device or a low noise flow controller that has a simple structure and high reliability and reduces fluid flow noise.
Conventional air conditioning apparatuses use a variable capacitance type compressor such as an inverter, and the like to cope with the fluctuations of an air conditioning load, and the rotational frequency of the compressor is controlled according to the magnitude of the air conditioning load. However, when the number of rotations of the compressor is reduced in a cooling operation, an evaporating temperature also increases, thus a problem arises in that the dehumidifying capacity of an evaporator is reduced or an evaporating temperature exceeds the dew point temperature in a room and dehumidification cannot be executed.
The following air conditioning apparatus is devised as a means for improving the dehumidifying capacity in a cooling low capacitance operation. FIG. 97 shows a refrigerant circuit diagram of a conventional air conditioning apparatus shown in Japanese Unexamined Patent Application Publication No. 11-51514, and FIG. 98 shows a sectional view of an ordinary throttle valve provided in FIG. 97. In the figure, numeral 1 denotes a compressor, 2 denotes a four-way valve, 3 denotes an outdoor heat exchanger, 4 denotes a first flow controller, 5 denotes a first indoor heat exchanger, 6 denotes a second flow controller, and 7 denotes a second indoor heat exchanger, and these components are sequentially connected through pipes and constitute a refrigerating cycle. Next, operation of the conventional air conditioning apparatus will be described below. In a cooling operation, the refrigerant ejected from the compressor 1 passes through the four-way valve 2, is condensed and liquefied in the outdoor heat exchanger 3, is reduced in pressure by a throttle device 11 because the two-way valve 12 of the first flow controller 4 is closed, is evaporated and gasified in the indoor heat exchanger 5, and returns to the compressor 1 again through the four-way valve 2. Further, in a heating operation, the refrigerant ejected from the compressor 1 passes through the four-way valve 2 inversely to the cooling operation, is condensed and liquefied in the outdoor heat exchanger 5, is reduced in pressure by the main throttle device 11 because the two-way valve 12 of the first flow controller 4 is closed, is evaporated and gasified in the outdoor heat exchanger 3, and returns to the compressor 1 again through the four-way valve 2.
In contrast, in a dehumidifying operation, the main throttle device 11 of the first flow controller 4 is closed, and the first indoor heat exchanger 5 is operated as a condenser, that is, as a reheater and the second indoor heat exchanger 7 is operated as an evaporator by opening the 2-way valve 12 and controlling the flow amount of the refrigerant by the second flow control valve 6. Thus, the indoor air is heated in the first indoor heat exchanger 5, whereby it is possible to execute a dehumidifying operation in which a decrease in the room temperature is small.
In the conventional air conditioning apparatuses as described above, since a flow control valve having an orifice is usually used as the second flow control valve disposed in an indoor unit, large refrigerant flow noise is produced when the refrigerant passes through the orifice and the indoor environment is deteriorated thereby. In particular, since the inlet of the second flow control valve is filled with a gas/liquid two-phase refrigerant in the dehumidifying operation, a problem arises in that the refrigerant flow noise is increased.
As a countermeasure for the refrigerant flow noise of the second flow control valve in the dehumidifying operation, Japanese Unexamined Patent Application Publication No. 11-51514 discloses such an arrangement that an orifice-like throttle flow path composed of a plurality of cut grooves 31 and a valve disc 17 is disposed in the valve of a valve seat 18 of a second flow control valve 6 of FIG. 98. Note that numeral 16 denotes an electromagnetic coil for moving the valve disc 17, 31 denotes a plurality of groove-like cut-outs cut in the opening 18 of a pipe acting as the valve seat and forming orifice-like throttle flow paths. This countermeasure for the refrigerant flow noise is devised to continuously flow the gas/liquid two-phase refrigerant through the plurality of orifice-like flow paths. However, there is a problem that this arrangement is not effective because the number of flow paths that can be disposed from processing point view is limited and the refrigerant flow noise is increased. As a result, an additional countermeasure of providing a noise insulating material and a damping material around the second flow controller 6 is required, so that a problem arises in that the cost is increased, and an installation performance and a cycle performance are deteriorated.
In contrast, in a flow controller used in an air conditioning apparatus shown in Japanese Unexamined Patent Application Publication No. 7-146032, porous members 32 acting as filters are disposed upstream and downstream of a throttle to reduce refrigerant flow noise as shown in the sectional view of FIG. 99. However, the porous members 32 are disposed at positions separated from a throttle section, so that they cannot continuously supply a gas/liquid two-phase refrigerant effectively to the throttle section, and thus a problem arises in that refrigerant flow noise is increased.
Further, FIG. 100 shows a sectional view of the arrangement of a flow controller used in an air conditioning apparatus disclosed in Japanese Unexamined Patent Application Publication No. 10-131681. Honeycomb pipes 37 acting as noise eliminators 36 each having holes communicating both the ends thereof are disposed upstream and downstream of a throttle to reduce refrigerant flow noise. FIG. 101 shows a sectional view of the honeycomb pipe. Since the area of each hole formed in the pipe is too small for a refrigerant to pass therethrough, a problem arises in that the hole is liable to be clogged by foreign materials flowing in a refrigerating cycle and the performance of the flow controller is lowered by a drop of the flow amount of the refrigerant. Further, another problem arises in that the refrigerant cannot be flowed without the occurrence of pressure loss because no bypass is formed for the throttle section.